How come you are only running them at 116Mhz...surely thats not right, are they PC3200? You can try bringing all but the CAS latency down, thats good, try one at a time by one each and test stability for each one with either memtest of run the SiSoft Sandra Memory Benchmarking test after each drop to save time and then run Memtest afterwards.
If you can get down to 2-3-3-6 that would be good, they may go lower or not but you wont know until you have tried. There is also voltage to take into consideration, as you tighten timings some sticks require a little extra voltage, what is the stock BIOS voltage now?